Formation of electrical dipoles during agglomeration of uncharged particles of hydrogenated silicon

Abstract

A new phenomenon of the formation of agglomerates having electric dipoles by agglomeration of originally uncharged aerosol particles is reported. The aerosol particles of hydrogenated silicon are formed via silane pyrolysis in a flow reactor. The size and morphology of agglomerates were analyzed by a transmission electron microscope. The agglomerate radius increased from 0.3 to 6 μm with the coagulation time increasing from 0.1 to 200 s (for T=873 K ). The mass M of these agglomerates is connected with the radius R via the equation M( g)=8.5×10 −14×[ R(μm)] 1.65. An imaging system coupled with a TV setup was used for direct observation of agglomerate coagulation and investigation of agglomerate movement in the electric field. The experimental results testify that the agglomerates are electric dipoles. It is suggested that this dipole moment arises due to the difference in Fermi energy of primary particles. The dipole moment is ∼3.5×10 −12 (units of CGSE) for the agglomerates with the radius R∼0.5 μm (T=873 K) . This dipole moment corresponds to the Fermi energy difference for coagulating particles ∼0.08 V .